Nonlinear Piezoelectric Structure for Ultralow-frequency Band Vibration Energy Harvesting with Magnetic Interaction

Abstract

In order to realize the energy harvesting structure working for an external perturbation or ultralow-frequency excitation, a continuous structure with adjustable nonlinearity is proposed and analyzed. The novel energy harvesting structure is consisted of a piezoelectric elastic beam and two pairs of magnets. Different from normal assembly of magnets in the same direction of the vibration motion, two pairs of magnets are assembled vertically to the vibration direction to induce adjustable nonlinear restoring force similar as the pre-deformed elastic components in so-called quasi-zero-stiffness system. With the model of magnets, the interaction energy and interaction force are obtained. Considering the the piezoelectric cantilever beam, it can realize a multi-stable vibration structure. The zero equilibrium is stable and the interaction energy there is very high, while there are two symmetry stable equilibriums with very low interaction energy. Thus, for small-amplitude and ultralow-frequency excitations from natural phenomenon such as dropping raining, the structure can have large-amplitude vibration with adjustable output frequency. At last, we realize the proposed vibration energy harvester by designing the structural according to the theoretical analysis. The structure of this study has potentially remarkable applications in intelligent and sustainable power generation.